/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.core.metrics;



import com.google.auto.value.AutoValue;

import com.bff.gaia.unified.sdk.metrics.GaugeResult;

import org.joda.time.Instant;



import java.io.Serializable;



/**

 * Data describing the gauge. This should retain enough detail that it can be combined with other

 * {@link GaugeData}.

 */

@AutoValue

public abstract class GaugeData implements Serializable {



  public abstract long value();



  public abstract Instant timestamp();



  public static GaugeData create(long value) {

    return new AutoValue_GaugeData(value, Instant.now());

  }



  public static GaugeData empty() {

    return EmptyGaugeData.INSTANCE;

  }



  public GaugeData combine(GaugeData other) {

    if (this.timestamp().isAfter(other.timestamp())) {

      return this;

    } else {

      return other;

    }

  }



  public GaugeResult extractResult() {

    return GaugeResult.create(value(), timestamp());

  }



  /** Empty {@link GaugeData}, representing no values reported. */

  public static class EmptyGaugeData extends GaugeData {



    private static final EmptyGaugeData INSTANCE = new EmptyGaugeData();

    private static final Instant EPOCH = new Instant(0);



    private EmptyGaugeData() {}



    @Override

    public long value() {

      return -1L;

    }



    @Override

    public Instant timestamp() {

      return EPOCH;

    }



    @Override

    public GaugeResult extractResult() {

      return GaugeResult.empty();

    }

  }

}